The use of fl exible ureteroscopy is required to improve stone-free rates in ureteroscopy for proximal ureteral stones

The main target in the treatment of Proximal Ureteral Stones (PUS) is to provide a high Stone-Free Rate (SFR) with low morbidity. There are now many treatment options for PUS as the result of the development of endourological techniques. These are Extracorporeal Shock Wave Lithotripsy (ESWL), Ureteroscopy (URS) (semirigid-fl exible, retrogradeantegrade), Percutaneous Nephrolithotomy (PNL), laparoscopic ureterolithotomy, and open surgery. Today, percutaneous antegrade URS, laparoscopic ureterolithotomy, and open surgery provide a high SFR when used in a small number of special cases, while ESWL and URS constitute the standard treatment of PUS [1]. URS, which has the highest SFR in the treatment of PUS with the development of fl exible ureteroscopes, is the fi rst treatment option for stones >10 mm and is also the fi rst treatment option with ESWL in stones <10 mm [2]. However, in developing countries, the fl exible ureteroscope and holmium Abstract

laser lithotriptor are not used due to their high costs, and the PUS may still have to be treated with a semirigid ureteroscope and pneumatic lithotriptor [3]. In this study, we aimed to evaluate the need for fl exible URS by retrospectively examining one surgeon's two-year experience of URS for PUS in a center where the fl exible ureteroscope and holmium laser lithotriptor are available. However, the fl exible ureteroscope is not used in all PUS cases in order to extend the lifetime of the fl exible ureteroscope due to economic considerations. We wanted to examine the SFR under these conditions.

Patients and methods
The medical records of all patients (48 patients, 49 renal units [RUs]) who underwent URS due to PUS by a single surgeon from November 2016 to November 2018 were evaluated retrospectively. The proximal ureter was defi ned as the part of the ureter between the Ureteropelvic Junction (UPJ) and the upper border of the sacroiliac joint. No specifi c exclusion criteria were applied.
All patients had a detailed medical history, physical examination, and laboratory tests, including renal function, complete urinalysis, and urine culture. All patients had Computed Tomography (CT) with stone protocol and plain X-ray of the Kidneys, Ureter and Bladder (KUB) on the morning of the operation. The location of the stone in all patients (as a distance from the UPJ), stone size, and the number of stones were recorded. In the postoperative period, all patients had a KUB on postoperative day one. Patients who had radiopaque stones had KUB and Ultrasonography (USG), and those who had radiolucent stones had CT in postoperative week 4. Patients who continued their follow-up for residual stones had USG in postoperative week8.
Success was accepted as patient with no stones or clinically insignifi cant residual fragments (<4 mm) observed at postoperative 4 th and 8 th weeks by radiological investigation. The size of the stones was taken as the longest axis on the CT. In the patients with postoperative residual fragments, the longest size in KUB was taken for radiopaque stones, and the longest axis in CT was taken for radiolucent stones.
The operation technique was as follows. All patients underwent surgery under general anesthesia in the lithotomy position. One gr of ceftriaxone was given as preoperative antibiotic prophylaxis. Additionally, 6.0/7.5 French (Fr) (Richard Wolf, Germany) and 9.5 Fr (Karl Storz, Germany) were used as the semirigid URS. Flex-X2 (Karl Storz, Germany) was used as the fl exible URS. In all patients, a semirigid ureteroscope was inserted into the ureter through a guidewire. At this stage, the patients with a narrow ureteral orifi ce were not entered and 4.7 Fr D/J catheters were placed, and the stone intervention was postponed after 3-4 weeks. In patients whose stone could be reached with semirigid URS, lithotripsy was performed with 30W holmium:YAG laser lithotriptor (Richard Wolf). The use of an anti-retropulsion device (stone cone or basket) was decided at the case level during the operation. Clinically signifi cant stone fragments were extracted. At the end of the operation, 4.7 Fr D/J or 5 Fr ureter catheters were placed, or no catheter was placed at the case level. We used fl exible URS in the following cases: when we went to UPJ with semirigid URS and did not see the stone because of push back to the kidney; when the stone or a signifi cant fragment was pushed back to the kidney while performing lithotripsy with semirigid URS; when we could not reach the stone with semirigid URS due to ureteric kink, or if we reached the stone and we could not perform lithotripsy suitable for the stone due to the angle in the ureter; and in cases with ipsilateral kidney stones. The 9.5-11.5 Fr or 11-13 Fr ureteral access sheaths were used in patients when ureter calibration allowed. In the other patients, lithotripsy was performed with 30W holmium:YAG laser lithotriptor (Richard Wolf) by entering sheathless into the

Results
Patient and stone characteristics of 49 RUs are detailed in Table 1.  Of course, these recommendations suggest that URS is